The present invention relates in general to fiber optic devices, and in particular fiber optic sensing devices.
Sensing devices are used in a wide range of technologies. Most automated mechanical and electrical apparatus include some sort of sensing capability. Particularly prevalent are sensors that can be read electronically. In many applications, such sensors provide electrical inputs used as feedback for control circuitry.
Electronic sensors are used to measure all manner of physical phenomena such as temperature, pressure, acceleration, voltage, electromagnetic fields, etc. The variety and adaptability of electronic sensors have resulted in such sensors being utilized in a wide assortment of products.
Some sensing applications pose more difficult challenges than others. For example in aeronautic and space applications, sensors are subjected to extremes of temperature, mechanical and electrical shock, electromagnetic interference, radiation, pressure, acceleration, etc. Also, the volatile fuels used in jet aircraft and rockets require that any sensors used in fuel areas must be carefully designed to prevent electrostatic discharge.
Sensors that are immune from risk of electrostatic discharge are very desirable in many fields, including aerospace and scientific fields. Although sensors for explosive or extreme environments have been developed, the design, manufacture, and testing of such sensors results in the devices being very expensive.
An apparatus and method that address the aforementioned problems, as well as other related problems, are therefore desirable.
To overcome limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a method and apparatus for passive sensing.
In accordance with one embodiment of the invention, a sensing device gathers light from one or more light sources, each light source having a unique primary wavelength. The sensor includes one or more mirrors to reflect light from the light sources. A collector mirror is arranged to reflect light from the mirrors. A light collector is arranged to gather light reflected from the collector mirror. A MEMS actuation member is coupled to the collector mirror. The MEMS actuation member is arranged to rotate the collector mirror in response to a change in a physical phenomena. Rotation of the collector mirror causes a change in the relative intensity of the primary wavelengths of the light sources at the light collector.
In another embodiment of the present invention, a sensing device arranged to gather light from a light source includes a source mirror arranged to reflect light from the light source. One or more collector mirrors are arranged to reflect light from the source mirror. One or more light collectors arc arranged to gather light reflected from the respective collector mirrors. A MEMS actuation member is coupled to the source mirror. The MEMS actuation member is arranged to move the source mirror in response to a change in a physical phenomena. Movement of the source mirror causes a change in the relative intensities of light measured at the light collectors.
The above summary of the present invention is not intended to describe each illustrated embodiment or implementation of the present invention. This is the purpose of the figures and the associated discussion which follows.